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FFR QFR CFR and coronary flow reserve ppt
- 1. PHYSIOLOGICAL LESION ASSESSMENT FFR,IFR – CONCEPT & TECHNICAL TIPS PRESENTED BY Dr Apoorva UNDER THE GUIDANCE Dr S S Kothari sir Dr Gajendra Dubey sir Dr Anand Shukla sir Dr Dinesh Joshi sir Dr Jignesh Vanani sir Dr Pankaj Singh sir
- 2. TEXT INTRODUCTION ▸ Coronary revascularizationis warranted only if a patient has one or more coronary artery stenoses that are hemodynamically important. ▸ Large randomized studies have shown that FFR is superior to angiographic assessment for this purpose. ▸ Studies have also shown that resting indices have diagnostic accuracy similar to that of FFR as independent measures of ischemia.
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- 4. INTRODUCTION • Myocardial perfusionpressure, normally the diastolic coronary pressure, equals aortic pressure minus the left ventricular diastolic pressure or CVP. • FFR is the “ratio of the maximal myocardial blood flow in the presence of a stenosis relative to expected normal flow in the absence of a stenosis.”
- 5. CONCEPT ▸ If flowincreases —> more drop in pressure past the stenosis. ▸ At maximal hyperaemia, flow increases and thus Pd further drops. ▸ Flow rises, but less than the potential rise had there not been a stenosis. Eg., flow increases x2, instead of x4 without a stenosis.
- 7. ▸ Larger territory ‣Higher flow at rest and especially with hyperaemia ‣ More Pd drop and flow drop past the stenosis. ‣ For the same stenosis severity (eg. 80%), a proximal LAD stenosis is more likely to be significant than a small diagonal stenosis. ‣ Collateral supply Also, for the same stenosis severity, length increases the significance of a stenosis (Poiseuille law).
- 8. SIGNIFICANCE ▸ FFR<=0.80 identifiesischemia with a very high specificity (100% if <0.75). ▸ FFR>0.80: PCI should be deferred. FAME TRIAL: patients with MVD undergoing PCI were randomised to angio guidance vs FFR guidance with deferral of stenting if FFR>0.80. FFR guidance improved combined MACE. ‣ FFR<=0.80: does not mandate stenting if angina atypical/infrequent (FAME 2 - FFR did not improve hard outcomes, death or MI at 3, 5 yrs, but improved angina and future revascularizations) ‣ Severe exertion angina + FFR <=0.80 = STENTING
- 9. TRIALS FAME TRIAL- FFRARM ▸ 50-70% stenoses: 35% FFR significant ▸ 70-90% stenoses: 80% FFR significant ▸ >90% stenoses: ~all significant Deferral is safe for FFR>0.80. The rate of MI occurring in a deferred lesion with FFR>0.80 was only 0.2% at 2 yrs in FAME 1. But, summation MI risk from all non significant lesions was still ~2% at 8 months and 8% at 5 yrs in FAME 2. Rate of MI from deferred lesion with FFR<0.80 was ~2-3% per yr in FAME 2, but still no overall MI/death benefit from stenting.
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- 12. TEXT IFR: INSTANTANEOUS WAVE-FREERATIO “Instantaneous pressure ratio, across a stenosis during the wave-free period, when resistance is naturally constant and minimised in the cardiac cycle.”
- 13. CONCEPT ▸ iFR usesthe concept that micro coronary resistance is lowest and flow is highest in diastole. In diastole, Pd/Pa ratio at rest drops the most and approximates flow ratio, even without using adenosine. ▸ iFR is a resting diastolic ratio. ▸ The cutoff of iFR significance is 0.89 ▸ 2 large trials (FLAIR & iFR-SWEDEHEART 2017) showed that iFR guided PCI was associated with long term outcomes similar to FFR- guided PCI. ~25% less lesions considered significant and stented by iFR (29% vs 37%). No difference in death, MI or unplanned revascularizations at 5yrs
- 16. TEXT IFR-FFR DISCREPANCIES ▸ iFRmay underestimate the severity of arteries with very large territories or healthy microcirculation, because the increase of flow in those lesions with/without hyperaemia is massive and thus, FFR would drop far more than a resting ratio. ▸ Hence, more lesions are significant by FFR than by iFR, but similar long term outcomes (FIGARO Study). ▸ LM may be better assessed by FFR. ▸ RCA may be better assessed by FFR. ▸ Low resting flow states ,may cause iFR-/FFR+
- 17. TEXT ▸ FFR-/iFR+ lesscommon, but is seen in patients with dysfunctional microvasculature/less hyperaemic response with adenosine (diffuse disease, elderly, smokers, CKD, diabetes). ▸ ~20% discordance between iFR and FFR (FIGARO study): FFR+/iFR- (14%, more so in RCA 23%) or FFR-/iFR+ (6%)
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- 20. EQUIPMENT PRESSURE MONITORING GUIDEWIRE ▸ Specially constructed 0.014” wire ▸ Pressure sensor incorporated into distal end, at 3 cm from tip ▸ Piezo-electric technology ▸ Eg. St.Jude Medical Phillips Volcano
- 21. METHOD INSTRUCTIONS ▸ 6 Frguide. NTG 100-200 mcg to eliminate epicardial vasospasm. ▸ Equalize Pa and Pd with wire sensor just at the guide tip. ▸ Place sensor 2-3 cm distal to the lesion, re-flush the catheter, not too distal. ▸ For FFR: hyperaemia with iv adenosine, large iv access (vs ic adenosine). ▸ For iFR: avoid measurements <30 sec after contrast flushing. ▸ Disengage guide during measurements. ▸ If borderline FFR, pull back and verify that Pa and Pd are equal (no transducer drift).
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- 28. ▸ One study(CCI 2015) has shown that even if you are not ventricularized, it is always good to disengage the guide during FFR measurement, as guide may be slightly obstructive —> you get more flow and more FFR drop with disengagement. ▸ The mean delta FFR after disengagement was 0.05+/-0.04 although most patients did not have obvious ventricularization.
- 31. IVUS= 4.5 mm2,but FFR was 0.91
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- 41. 2. DIFFUSE DISEASE ▸ IfFFR <=0.80 but pressure pullback reveals a gradual decline in pressure without a focal drop, the patient may not be served by PCI (but may be by CABG). ▸ This may be seen in patients with mild or moderate diffuse disease and small coronary arteries: 8-10% of arteries with mild diffuse lesions have a graded continuous fall in pressure along the arterial length with FFR<0.75, explaining myocardial schema and angina without angiographically obstructive disease.
- 44. 3. LEFT MAIN DISEASE HamilosM et al. Circ 2009
- 47. With MLA <6mm2, 22.4% had FFR-/iFR- With MLA >6 mm2, 13.6% had FFR+/iFR+ Best to use both iFR and FFR in LM +/- IVUS. Revascularize if 2/3 are significant
- 48. 4. NON-CULPRIT ARTERY INNSTEMI/STEMI
- 49. 5. AORTIC STENOSIS Yousif Ahmadet al. JACC Cardiovasc Interv.2018 October
- 50. TEXT BEST USED IN: FFRiFR LM/prox LAD Serial disease Young patient with focal disease Aortic stenosis Healthy microcirculation Microvascular dysfunction
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- 53. Falsely - FFRTruly - FFR Falsely + FFR Guide not disengaged Side hole guide Small territory Diffuse disease Severe hypotension Old MI with little viable tissue Lack of equalisation Pressure drift Advanced heart failure Severe stable microvascular disease Accordion effect Insufficient hyperaemia
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Editor's Notes
- #4 During maximal hyperemia (adenosine) coronary resistance is at the lowest level and remains constant ,so flow is directly related to measured pressure. Ohm s law an FFR of 0.7 means that in a given coronary artery with a stenosis, it is possible to reach only 70% of the maximal blood flow had the artery been free of atherosclerotic lesions.
- #7 poiseuille= viscosity x length/ r4
- #8 FAME 2: stenting FFR<0.8 (compared to mmx) did not improve hard outcomes, death or MI at 3, 5 yrs, but improved angina and future revasc.
- #9 Fame trial enrolled stable CAD patients Fame 2= deferred stenting unless necessary cz PCI itself had 2-3% risk of stent thrombosis etc
- #10 Why loss of dicrotic notch?- LCA flow pred in diastole, increased flow, more drop in pressure in diastole.
- #12 Concept: MVR is lowest and flow highest in diastole. RESTING DIASTOLIC RATIO
- #13 0.89 cz no hyperaemia Cz of no hyperaemia, iFr can underestimate in large territories/ healthy microvasc.
- #15 iFR guided PCI was associated with long term outcomes similar to FFR-guided PCI
- #16 RCA- max flow in late systole and early diastole. For iFR- mid diastole. Low resting flow states (Brady/beta blockers)- can have low resting flow rate, but high on hyperaemia
- #18 If you defer PCI in discordant FFR/IFR, outcome is same as that in both negative FFR/IFR THUS, NO need to check both, unless in LM
- #20 piezoelectric= using crystals to convert mechanical energy (pressure) into electrical energy and vice versa Pressure generates electrical charges in crystals (quartz)
- #21 Equalise: remove wire introducer from tuohy (drops Ao pressure) Flush catheter and remove contrast ic= rca 50 mcg/100 lca
- #25 This is pressure drift due to 1. Zeroing error 2. Transducer drift
- #26 Elaborating on ostial dampening- ventriculization of Pa- disengage guide.
- #27 Difficult to recognise this phenomenon with side hole catheter, thus not recommended.
- #28 CCI- cathetrization and cardiovascular interventions
- #30 For extra support during disengaging guide
- #32 Pd can ventriculize but Pa SHOULD NEVER
- #33 Wait for stable hyperaemia. Initial Pd drop is high cz coronary micro vasodilator earlier than systemic micro. Wait for 30 sec and then measure FFR value
- #35 Local pressure drop is not true FFR for that lesion. It is underestimated, since max hyperaemia is not achievable. P2 affects P1 more than other way round. P2 is still an adequate estimate in summation, cz it is closer to microcirc.
- #36 P2 prevents max hyperaemia for P1, thus FFR not accurate for P1 And P1 is far away from microcirc. P2 still better accuracy for FFR.
- #37 Thus, we get a summation FFR, do pullback and look for stair step pressure drop. Fix the lesion with more drop, in this case P2,fix P2, later assess P1, fix if significant.
- #38 Serial stenoses crosstalk is exaggerated by hyperaemia/high flow. It may be better to use static non-hyperaemic parameters, like iFR to assess which lesion is most important This study, iFR at baseline across lesion, correlates well with iFR across fixed lesion.
- #39 Across lesion- drop of 0.09. Baseline iFR 0.85. After stenting- 0.85+0.09= 0.94 Actual post-PCI iFR= 0.92 linear correlates.
- #40 Baseline iFR= 0.41 Drop of 0.51 Expected 0.92, actual 0.88
- #41 Cabg provides diffuse flow rise
- #42 Gradual decline in diffuse ds
- #45 LM-FFR is falsely increased( false negative) in presence of severe LAD/LCX disease (serial stenoses concept). Prevents max hyperaemia. What can we do? If summation FFR is significant and the 2nd stenosis is in prox LAD—> consider CABG.
- #46 If IVUS <6 mm2= revasc Ilitro trial: If discordant, and if either ffr/ifr += revasc, since in these pts, IVUS was significant,
- #47 IVUS to be done if concomitant prox LAD/LCX lesion
- #48 Frame MI: FFR guided> Flower MI: Non inferior DATA SMALL COMPARED TO STABLE CAD
- #49 Intermediate lesion in AS pt, candidate for TAVR. With FFR, dramatic difference post procedure. Serial stenosis concept= iFR better And adenosine C/I
- #51 TARGET (FFR) AND FINE-PCI TRIAL(iFR)
- #53 Accordion effect: tortuous artery, causing pseudo stenoses which induce pressure gradients.